(11c) Optimum Design of Membrane Reactor Which Is Used for Hydroxylation of Benzene

Computational fluid dynamics has already become a widely used and indispensable design and optimization tool in many technical areas. In the present work, the CFD simulations have been coupled with complex chemical reactions to model a membrane tubular reactor which is used to produce phenol from benzene.

Direct hydroxylation of aromatic compounds (Benzene) was achieved using a developed pd membrane reactor in which the palladium membrane is thin enough to allow permeation of hydrogen below 250 o c. In this reactor, the active oxygen species is formed on the surface of palladium via the reaction between oxygen and permeated hydrogen from opposite sides of the membrane hydroxylation occurs on the surface of palladium via reaction of benzene and active oxygen. Following are the reactions occur in the membrane reactor:

C6H6 + OHo → C6H5OH Reaction1

C6H5OH + OHo → C6H4(OH)2 Reaction2

Based on the data provided by the experiments, a mathematical model has been constructed to conduct a simulation which leads us to an optimum design of the tubular membrane reactor. The two geometrical factors which are concerned in the present study are the reactor length and diameter, respectively. Figure 1 shows how the concentration of the product (phenol) and conversion of benzene changing with increasing the reactor length, respectively. Although increasing the reactor length increase the conversion of benzene to phenol but the concentration of the phenol start to decrease as the reactor length exceeds the 60mm. This happens due to the reaction 2 which compete with reaction1. The essence of the present work lies under the optimization of the membrane catalytic reactors which is a novel work on its kind.

Figure 1 Concentration of phenol x and conversion of benzene ? versus the reactor length